Hi-lo valve

ABSTRACT

A subsurface safety valve well tool securable in a well conduit for controlling flow of fluid through the bore of the conduit. An increase or decrease in the well pressure from the normal flowing pressure of the well operates a rotatable ball valve to block flow of fluid through the conduit. Increasing and then decreasing the pressure in the bore above the ball valve rotates the valve to enable flow of fluid through the conduit.

0 mted States Patent [191 [111 33 Mott Jan. 29, 1974 HI-LO VALVE 1 3,642,070 2/1972 Taylor .1 166/224 3,509,913 5/1970 Lewis.... [75] Inventor' James Houston 3,398,762 8/1968 Fredd 251/58 x [73] Assignee: Hydril Company Primary Examiner-Harold W. Weakley [22] Flled' 1972 Attorney, Agent, or FirmPravel, Wilson & Matthews [21] Appl. N0.: 214,679

[57] ABSTRACT 152] U.S. C1 251/58, 137/458, 137/494, A subsurface safety valve well tool securable in a well 166/224 conduit for controlling flow of fluid through the bore [511 Int. Cl. Fl6k 31/63 of the conduit. An increase or decrease in the well [58] Field of Search251/58; 166/224; 137/458, 460, pressure from the normal flowing pressure of the well 137/494 operates a rotatable ball valve to block flow of fluid through the conduit. Increasing and then decreasing [56] References Cited the pressure in the bore above the ball valve rotates UNITED STATES PATENTS the valve to enable flow of fluid through the conduit. 3,310,] 14 3/1967 Dollison 166/224 22 Claims, 24 Drawing Figures 3a\ l. E

3// i y I, -J/f A l A A /r-J/6 3/c\ J/a x C v v PATENTED JANZQ 19M SHEET DlBF i0 PATENTEBJAN 29 ISM SHEET 0% OF '10 0 &/// 1 I I PNETED M29 [974 3, 788 594 SHEET UBUF W SHEEI 080F 10 PATENTEDJAN 2 91974 sum UBOF 10 I PAIENTED ES 3,788,594

sum IUUF 10 Ill-L VALVE CROSS REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION through the string or conduit when the surface control equipment was destroyed, damaged, or otherwise rendered inoperable before shutting in the well. Prior subsurface safety valves for controlling a full bore flow in a well, resulting from the destruction of the surface controls and the like, have been unreliable in wells having high allowable production rates due to the relatively small well pressure difference between normal well-flowing pressure and full bore well-flowing pressure.

An object of the present invention is to provide a new and improved well tool.

Another object of the present invention is to provide a new and improved subsurface safety valve operable by changes in the well pressure.

SUMMARY OF THE INVENTION A subsurface well tool securable in the bore of a production tubing for controlling flow of fluid through the bore of the tubing includes a flow control assembly and a ball-type bore closure means. The ball is moved to and locked in an openposition by means with the flow control assembly for enabling flow through the bore of the tubing by sequentially increasing and decreasing the pressure in the bore of the tubing above the ball. A subsequent increase or decrease in the pressure in the bore of the tubing fromthe normal well-flowing pressure operates a reference chamber pressure biased piston means to release and effect rotation of the ball to the closed position to block flow through the bore. The flow control assembly includes means for delaying closing movement of the ball when the well pressure decreases below the normal flowing pressure until the pressure reaches a predetermined value.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A, 1B, 1C, 1D, 1E, and IF are side views, partially in section, from top to bottom of the well tool of the present invention in the closed position;

FIGS. 2A, 2B, and 2C are views similar to FIGS. 1B and 1C with the preselected pressure in the reference chamber;

FIGS. 3A, 3B, 3C, and 3D are side views partially in section, illustrating movement of the valve to the open position; I

FIGS. 4A, and 4B are views similar to FIGS. 3A and 3B illustrating the valve in theopen position;

FIGS. 5A, 5B, and 5C are side views illustrating the valve closed by increased pressure in the well;

FIGS. 6A and 6B are side views similar to FIGS. 5A and 5B illustrating the valve closed by decreased pressure in the well;

FIGS. 7, 8, and 9 are views taken along lines 7-7, 88, and 9-9, respectively, of FIG. 1C; and

FIG. 10 is a view taken along line l0-l0 of FIG. ll).

DESCRIPTION OF THE PREFERRED EMBODIMENTS Attention is directed to the FIGS. where the well tool of the present invention is illustrated in greater detail. The well tool is connected at its upper end, as will be explained, to a mandrel tool (not shown) and the connected tools are then secured in the bore of a conduit or tubing (not illustrated) by the mandrel at a subsurface location to control the flow of fluid through the bore of the tubing. Reference is made to my co-pendin g application, Ser. No. 214,734, which illustrates and sets forth in greater detail the relationships between the tubing, the mandrel, and the well tool.

The well tool, generally designated S, includes a flow of the tubing. The bore closure means B is moved to the open position to enable flow through the bore of the tubing and is moved to the closed position to block flow through the bore of the tubing as will be explained.

As illustrated in FIGS.'1A, 1B, 1C, 1D, 1E, and IF, the flow control assembly F for supporting and effecting movement of the bore closure means B includes an elongated tubular member 31, a movable slide means 33, a piston means and a means for providing a reference urging on the piston means. The tubular member 31 includes threads 31a formed on the outer surface adjacent the upper end of the member 31 (FIG. 1A) to connect the well tool S with the mandrel. The

tubular member 31 extends downwardly from the man- I axis to provide a flow passage through the flow control assembly F.

The means for providing a reference urging on the piston means includes a pressure reservoir means 32 comprising a securing ring 32a, a base sleeve 32!), a cap sleeve 320, a reservoir sleeve 32d, and a diaphragm 34. The ring 32a (FIG. 1A) is locked within a recess 31c formed in the outer surface of the tubular member 31 for securing the reservoir means 32 with the tubular member 31. For ease of assembly the base sleeve 32b and the cap sleeve 320 are secured together by threads 322 while threads 32f secured the reservoir sleeve 32d with the sleeve 32b. The sleeves 32b and 32c engage the protruding portion of the ring 32a to prevent longitudinal movement of the reservoir means 32 relative to the tubular member 31. Engagement of the tapered upwardly facing annular surface 32g of the snap ring 320 with the cap sleeve 32c maintains the ring 32a in the recess 310 of the member 31. An O-ring 32h seals between the sleeve 32b and the sleeve 32d adjacent the threads 32f to prevent leakage of fluid therebetween.

The flexible diaphragm member 34 is positioned within the concentric annular space formed between the inner surface of the reservoir sleeve 32d and the outer surface of the tubular member 31 for containing a charged reference fluid pressure as will be explained. The lower end of the sleeve-shaped diaphragm member 34 (FIG. 1B) is sealed to the inner surface of the sleeve 32d with a pair of O-rings 340 located in corresponding recesses in the outer surface of a ring member 34b secured to the diaphragm 34. The ring 34b is spaced from the outer surface of the member 31 to form an annular flow passage therebetween. The upper end of the diaphragm 34 (FIG. 1A) has a ring member 34c secured to the sleeve 32b by threads 34c. The diaphragm 34 is sealed to the outer surface of the tubular member 31 to prevent leakage of fluid therebetween by an O-ring 34d located in a recess in the inner surface of the ring 346.

An expansible charged fluid reference pressure reservoir 37 is thus formed by portions of the inner surface of the sleeve 32d, the lower shoulder and outer surface of the sleeve 32b, the outer surface of the ring 34e, and the outer surface of the flexible diaphragm 34.

As illustrated in FIG. 1A, the pressure reservoir means 32 also includes a means 35 for filling or charging the reservoir 37. The means for filling the reservoir 35 includes a threaded refill connection port 35a communicating through an annular channel 35b with a port opening 34f which are, all located in the sleeve 32b. A flapper check valve member 35c, secured at the upper edge to the sleeve 32b enables communication or flow through the port 34f into the reservoir 37 by flexing away from the opening 34f, but prevents flow from the reservoir 37 by moving to cover the port 34f.

The piston means 70 (FIGS. 18 and 1C) is concentrically mounted on theouter surface of the tubular member 31 and is longitudinally movable relative thereto in response to the urgings thereon. The piston or plunger 71 is preferably made in two portions for ease of assembly and includes an upper portion 71a connected to a lower portion 71b to form a sleeve-like unit. The upper portion 71a includes a constant diameter movement guiding inner surface 710 adjacent the outer surface of the tubular member 31, a downwardly facing pressure responsive annular shoulder surface 71d, an outer surface portion 7le having a recess 7lfformed therein and an upwardly facing pressure responsive annular surface 71g. The sleeve 32d is sealed to the piston 71 to prevent the passage of fluid therebetween by an O-ring 32i while an O-ring 17111 effects a seal between the plunger 71 and the tubular member 31. Preferably, the annular pressure responsive surfaces 71d and 71g have equal effective surface areas for the pressures to urge on, which is provided by sealing the piston 71 above the taper of the surface 7le with the O-ring 32i. The sleeve 71g includes a downwardly facing shoulder 71h for engaging the lower portion 71b to impart downwardly movement thereto. The lower sleeve portion 71b is secured to the upper portion 71a by a detent nember 71k with an upper annular shoulder 71i engaging the downwardly facing shoulder 71h for imparting the downwardly movement to the sleeve 71b. The engagement of the shoulder 7111 and 711' also aligns an annular recess 71j in the inner surface of the sleeve 71b with the recess 71f in the upper portion 710 to enable the gapped spring detent ring 71k within the annular recess 71fto expand radially into the recess 71j to secure the sleeve portions 71a and 71h together. A port 71m extends through/the sleeve 71b adjacent the detent 71k to enable disasslembly of the plunger 71 by providing a means for moving the detent ring 71k out of the recess 71j. The plunger 71b includes a constant diameter inner surface 7ln spaced from the member 31 and a port 71 formed through the sleeve 72b adjacent the shoulder 71d for communicating the well pressure to the pressure responsive surface 71d.

The portion of the pressure reservoir means 32 adjacent the piston pressure responsive surface 71g and de fined by the inner surface of the diaphragm 74 and the outer surface of the member 31 form a chamber 75 which is filled with oil or another liquid for transmitting the urging of the charged pressure in the chamber 37 to the piston 71 for urging the piston 71 to move downwardly. The well pressure communicated through the port 71p urges on the surface 711] for urging the plunger 71 to move upwardly in response to the well pressure in the'bore of the tubing.

As illustrated in FIGS. 1C, 10, 1E, and IF, the slide means 33 for effecting movement of the bore closure means B includes three sleeve portions threadedly secured together to form a sleeve concentrically mounted with the tubular member 31 exterior and movable relative thereto between an upper position (FIGS. 1C, 1D, 1E, and IF) and a lower position (FIGS. 3B, 3C, and 3D). The slide means 33 includes an upper sleeve portion 33a (FIGS. 1C and 1D) threadedly secured to the upper end of the intermediate sleeve portion 33b (FIG. 1E). The lower end of the sleeve 33b is threadedly secured to the upper end of the lower sleeve portion 330 (FIG. 1F). Rotation of the threaded sleeves 33a, 33b, and 330 is blocked by two threaded pin members 33d to prevent disengagement therebetween. The connected sleeves 33a, 33b, and 330 form a longitudinally extending bore 34 which communicates with bore 25 to provide a flow passage through the flow control assembly F. The upper sleeve 33a has a stepped inner surface to form an upwardly facing annular shoulder surface 332 (FIG. 1C) while the inner surface of the lower sleeve 330 (FIG. 1F) is also stepped to provide an upwardly facing flat annular shoulder surface 33f and an upwardly facing tapered annular shoulder surface 33g. A chevron packing ring 31f (FIG. 15) is secured between the upper shoulder of the seal ring 310 and a ring packing keeper 31g for sealing between the tubular member 31 and the movable slide sleeve 33 to block passage of fluid therebetween.

The bore closure means B is movably disposed in the bore 34 of the slide 33 adjacent the middle sleeve portion 33b (FIG. 1E). The bore closure means B includes a rotatable ball-type valve 40 and a seat ring 41 located above the ball 40. The ball 40 has a bore 400 therethrough for enabling flow of fluid through the bore 34 when the ball 40 is in the bore aligned or opened position (FIG. 4B) and is rotatable to a transverse or closed position (FIG. 1E) blocking flow of fluid through the bore 34. The ball 40 includes an outer spherical surface 40b having a pair of parallel flat circular shaped surface portions 400. Each of the parallel portions 40c has an elongated radially extending recess 40d formed therein for pivotally securing the ball 40 in the bore 34 and for imparting rotational movement to the ball 40 as will be set forth in greater detail hereinafter.

The seat ring41 includes a lower annular seating surface 41a engaging the spherical surface 40b of the ball 40 for sealing thereto to block flow of fluid upwardly through the bore 34 of the slide 33 around the ball 40. The seat ring 41 is longitudinally movable relative to both the slide 33 and the tubular member 31 and has an upper annular shoulder 41]) for engaging the lower annular shoulder 31a of the member 31c for limiting upward movement of the seat ring 41 and the ball 40. A packing ring 410 slidably seals between the inner surface of the slide 33 and the outer surface of the seat ring 41.

The flow control assembly F includes means for effecting movement of the bore closure B to the open position for enabling flow through the bore comprising a pivot means 42 and an actuator means 43. The pivot means 42 (FIG. 1E) includes a pair of longitudinal axis aligned elongated pins 42a threadedly secured with the slide 33 at an eccentric position for extending into the corresponding recesses 40d in the flat surfaces 400 of the ball 40. Relative longitudinal movement between the ball 40 and the pins 42a will effect a cranking action to rotate the ball 40 to and from the open and closed positions. Upwardly movement of the ball 40 relative to the pins 42a rotates the ball 40 to the open position and movement of the ball 40 downwardly relative to the pins 42a rotatesthe ball to a closed position.

The actuator means 43 includes a movable sleeve 44 concentrically disposed in the lower portion of the bore 34 of the slide 33 for engaging the ball 40 to impart an urging to effect upwardly longitudinal movement'of the ball 40. The sleeve 44 has an arcuate upper annular shoulder 44a (FIG. 1E) for engaging the lower portion of the spherical outer surface 40b of the ball 40 to transmit the urging to the ball 40. The outer portion of the sleeve 44 has a collar 44b thereon (FIG. 1F) having a lower flat spring shoulder 44c and an annular tapered shoulder 44d engaging the shoulder 33g of the slide 33 to provide a lower stop for the sleeve 44. A spring means 44e is positioned between the shoulder 33f and the shoulder 44c for urging the sleeve 44 to move upwardly.

Means for effecting movement of the ball 40 to the closed position includes the slide 33, the pivot pins 42a and an urging means 50. The urging or spring means 50 for urging the slide 33 to move upwardly to effect closing rotation of the ball 40 (FIGS. 1D and IE) is concentrically mounted in the annular area between the tubular member 31 andthe slide 33. The lower end of the spring means 50 is mounted with the tubular mem ber 31 by engagement with a snap ring spring keeper member 51 secured within a recess 3111 in the outer surface of the tubular member 31. The upper end of the spring means 50 engages a lower annular shoulder 52a of a movable spring keeper ring 52, concentrically mounted on the tubular member 31. The keeper ring 52 has an upper shoulder 52b engagableby a lower shoulder 53a of a sleeve member 53 to transmit the urging of the spring 50 to the sleeve 53. The sleeve 53 (FIG. 1D) is longitudinally movable relative to the tubular member 31 and is partially guided in such movement by an upper inner surface 53d engaging the outer surface of the tubular member 31. A snap ring 54 semember 53 has an annular recess 53e formed in the upper outer surface 53g to receive a gapped spring detent ring 55 therein. When the ring 55 is aligned with an annular recess 33h formed on the slide portion 330. the detent ring 55 expands outwardly to move into the recess 33h with an upper shoulder 55a of the ring 55 engaging a downwardly facing shoulder 331' of the an nular recess 33h formed in the slide. The engagement of the shoulders 331' and 55a transmits the upward urging of the spring means from the guide sleeve 53 to the slide 33. A port 33 extends through the slide 33 to enable disengagement of the slide 33 by forcing the detent ring from the recess 33h. The guide member 53 has a pairof O-rings 53f mounted in recesses in the outer surface 53g to effect a seal to the slide 33 above and below the port 33j for preventing leakage of fluid therebetween. The spring 50 is made substantially stronger than spring 44s for overcoming the urging of spring 44e to compress the spring 44a and maintain the slide 33 in the upper position.

As illustrated in FIG. 1C, the flow control assembly F includes means for releasably locking the bore clo sure means B in the open position comprising the annular shoulder 332 of the slide 33, a plurality of detent balls mounted with the flow control assembly F and a latch or locking sleeve 61. The locking sleeve 61 is concentrically mounted with the outer surface of the tubular member 31 and is longitudinally movably relative thereto and extends between an upper annular shoulder 61a and a lower flat annular shoulder 61b. The sleeve 61 has a constant diameter inner surface portion 61c for guiding the movement of the sleeve 61 and constant diameter outer surface portion 61d with an outwardly extending annular collar 6le formed thereon. The collar 61e provides an upwardly facing flat annular shoulder 6lfengagable by a lower annular shoulder 71t of the piston means 71 for effecting downward movement of the sleeve 61. The sleeve 61 has an elongated aperture or slot 61g to receive an inwardly extending finger 71:; secured with the piston 71 for connecting and radially aligning the sleeve 61 with the piston 71, while enabling limited relative longitudinal movement therebetween. The sleeve 61 has a plurality of spaced windows 61h extending through the sleeve 61 above the collar 61e for a purpose to be set forth more fully hereinafter. The sleeve 61 has a plurality of window openings 61i beneath the collar 6le to enable inwardly extending portions of a fixed ring member 74 extending through the sleeve 61 to secure the sleeve 74 with the tubular member 31 while enabling longitudinal movement of the sleeve 61. As illustrated in FIG. 8, the sleeve 61 is slotted to provide a plurality of three movement enabling clearance windows 61j through which a corresponding plurality of three inwardly projecting fingers a of a fixed split ring 65 extend to secure the split ring 65 to the tubular member 31. The sleeve 61 has a plurality of window openings 61k and a corresponding plurality of open-ended slots 61m formed adjacent the lower end of'the sleeve 61 to control movement of the detent balls 60. The downwardly facing upper edge of the slot 61m and the upwardly facing lower edge of the window 61k are tapered to force the balls 60 to move outwardly when they are engaged as will be set forth hereinbelow.

The locking sleeve 61 includes a biasing spring means 62 located above the sleeve 61 for urging the sleeve 61 to move downwardly. The spring is secured to the tubular member 31 by a ring-shaped spring keeper member 62a positioned above the spring 62. The member 62:: is secured to the outer surface of the tubular member 31 by inwardly extending fingers fitting within an annular recess 31i in the outer surface of the tubular member 31. The lower end of the spring 62 engages a movable spring keeper 62b concentrically mounted on the outer surface of the tubular member 31 above the sleeve 61 for imparting the urging of the spring 62 to the sleeve 61.

Mounted concentrically with and adjacent the lower exterior surface of the locking sleeve 61 is a sleeve member 63 which is fixed relative to the tubular member 31 to form a portion of the flow control assembly F (FIGS. 38 and 3C). The sleeve 63 is secured with the tubular member 31 by a lower annular shoulder 63a engaging an upper shoulder 64a of a ring member 64 having inwardly extending finger portions 64b securing the ring member 64 in a recess 3lj on the outer surface of the tubular member 31. Engagement of the sleeve 63 with the ring member 64 blocks downward movement of the sleeve 63 relative to the tubular member 31. The sleeve 63 is secured with the tubular member 31 against upward movement by engagement with a fixed split ring 65. The sleeve 63 is sealed to the slide 33 by an O-ring 63c positioned in the recess in the outer surface of a collar portion 63d to block passage of fluid therebetween. The sleeve 63 has a plurality of window openings 63b extending therethrough with a corresponding plurality of detent balls 60 positioned within the openings 63b. The diameter of the balls 60 is greater than the thickness of the sleeve 63 adjacent the opening 63b wherein the balls 60 protrude either inwardly or outwardly of the sleeve 63.

As illustrated in FIGS. '38 and 8, the sleeve 63 has a pair of upwardly extending finger portions 63g which extend into corresponding recesses formed in the outer surface of the fixed split ring member 65. The inwardly projecting fingers 65a of the split ring 65 extending through the windows 61j of the sleeve 61 thereby effect radial alignment of the plurality of window openings 63b in the fixed sleeve 63 and the windows 61k and slots 61m of the locking sleeve 61 for enabling the balls 60 to protrude inwardly. When the slide 33 is in the lower position enabling the ball 40 to rotate open, the shoulder 33e is positioned below the ball detents 60. This enables the spring 62 to urge the sleeve 61 downwardly to thereby wedge the balls 60 to protrude outwardly above the shoulder 33e with the tapered downwardly facing shoulders of the slots 61m. The urging of the spring 62 will then move the sleeve 61 downwardly beside the balls 60 to lock the balls 60 with the outer surface 61d to protrude outwardly where they will engage the shoulder 33c to block the slide 33 from moving upwardly to rotate closed the ball 40. Subsequent longitudinal movement of the locking sleeve 61 to align the windows 61k or the slots 61m with the detent balls 60 will enable the spring 50 urging on the slide 33 to wedge the released balls 60 to move inwardly and move the slide 33 to the upper position effecting closing rotation of the ball 40.

The locking sleeve 61 is operably connected with the corresponding plurality of tapered edge window openings 71r in the lower sleeve 71b of the plunger 71. A corresponding plurality of detent balls 73 having a greater diameter than the wall thickness of the piston 71 are located in the'plurality of windows 7lr to protrude inwardly or outwardly of the piston 71. The lower annular shoulder 71! of the piston 71 is adapted to engage the upwardly facing shoulder 61f for urging the locking sleeve 61 to move downwardly in response to pressures urging on the piston 71 to align the windows 61k with the balls 60 to release the slide 33.

A latch slide or detent connecting means 72 (FlG. 1C) is a longitudinally movable sleeve for controlling movement of the detent balls 73. The upper movement limit stop for the member 72 is provided by engagement with an upper stop ring 74 secured to the tubular member 31 by inwardly projecting fingers 74a extending through the slots 611' in the sleeve 61 to the tubular member 31. The member 72 has a stepped inner surface 72a having an inwardly projecting collar 72b to provide an upwardly facing annular shoulder surface 720 for engaging the lower shoulder of the stop ring 74. The detent connecting means includes a spring means 72d concentrically mounted with tubular member 31 between a downwardly facing annular shoulder 722 of the collar 72b and the fixed split ring 65 for normally biasing the latch sleeve 72 to move upwardly to the position illustrated in FIG. 1C. Engagement of the detent ball 73 with a tapered annular shoulder 72f on the inner surface 72a will enable the plunger 71 to move the latch slide 72 downwardly with the plunger 71 until the detent balls 73 are aligned with the plurality of windows 61h in the sleeve 61 at which time the tapered annular shoulder 72f will cam or wedge the balls 73 inwardly into the windows 61h enabling the spring means 72d to move the latch sleeve 72 upwardly. The upwardly movement of the latch sleeve 72 locks the balls 73 in the windows 61h of the sleeve 61 for connecting the locking sleeve 61 with the piston 71 to move the locking sleeve 61 with the piston 71 as the piston 71 moves in response to the well pressure.

Concentrically mounted with the outer surface of the tubular member 31 below the sleeve 61 in a balance means or means for delaying the valve from closing when the pressure in the bore of the tubing caries from the preselected pressure until the pressure varies to a predetermined pressure less than the preselected pressure. As illustrated in FIGS. 2C and 10, the balance means includes a movable ring member 66 having a plurality of upwardly extending finger portions 66a positioned between the inwardly extending fingers 64b of the fixed ring 64 for providing movement enabling clearance to the ring 66 as well as an upper movement limit stop. The upwardly extending fingers 66a provide an upwardly facing annular shoulder 61b adapted to engage the downwardly facing slotted annular shoulder 61b of the locking sleeve 61. The ring 66 is longitudinally movable between an upper position (FIG. 1C) and a lower position (FIG. 2C). It will also be appreciated that the fixed ring 64 also provides a lower movement limit stop for the locking sleeve 61. The means for delaying the valve from closing includes a spring means 67 for urging the balanced member 66 normally to move upwardly which is concentrically mounted with the tubular member 31 beneath the balanced member 66. The spring means 67 includes a fixed spring retainer member 67a secured to the tubular member 31 and an adjustment ring 67b threadedly secured to the keeper 67a. Rotation of the adjustment ring 6712 relative to the keeper 67a compresses the spring means 67 to enable adjustment of the upwardly urging force imparted to the ring 66 for delaying downwardly movement of the locking sleeve 61. A threaded keeper pin 670 blocks rotation of the adjustment member 67b relative to the keeper 67a after the urging or upward force of the spring 67 has been set to a predetermined pressure. urging.

The flow control assembly F also includes a means for equalizing the urging of the well pressure on the flow control housing to provide a larger flow passage through the bore of the well tubing adjacent the flow control assembly F by reducing the thickness of the flow control assembly F. The means for equalizing the urging of the well pressure includes a balance piston 81 and a balance chamber 82. The balance piston 81 (FIG. 1B) is a ring-shaped member positioned between the tubular member 31 and the surface 71n of the plunger 71 adjacent the shoulder 71d and is longitudinally movable relative to both the plunger 71 and the tubular member 31 in response to pressure urgings thereon. The balance piston 81 is sealed by a pair of rings 81a and 81b to the inner surface 71n of the plunger 71 and the outer surface of the tubular member 31, respectively, to block leakage of fluid about the balance piston 82. Sealing about the balance piston 81 provides an upwardly facing pressure responsive annular surface 81c and a downwardly facing pressure responsive annular surface 81d which effect movement of the balance piston 81 in response to the pressure differential urging. The balance chamber 82 forms well pressure equalizing surfaces in the flow control assembly F and is defined by the outer surface of the tubular member 31 including the upper shoulder of the seal ring 316 to packing 31f(FlG. 1E), a portion of the inner surface of the slide 33 (FIGS. 1C and 1D), the surface portions of the sleeve 63 between the O-rings 63c and 63e, the inner surface of the latch slide 73, the lower portion of the plunger 71 inside the O-ring 71s and the lower shoulder of the balance piston 81. By filling the chamber 82 with a liquid, such as oil, the pressure of the oil in the chamber 82 will be maintained equal to the pressure in the bore of the tubing communicated through the port 71p to the surface 810 by an equalizing movement of the balance piston 81 to effect an equal pressure urging by the oil in the chamber 82 on the surface 81d. The oil in the chamber 82 provides a clean envilocation where the tool S is to be secured in the production tubing is first determined. The normal well flowing pressure is always less than the shut-in pressure and will be greater than the full bor flowing pressure. The magnitude of these pressures and their difference will vary from well to well. As an example for purposes of this disclosure, the well will have a normal subsurface flowing pressure of 2,500 psi, a subsurface shut-in pressure of 3,000 psi and a full bore flowing pressure of 2,200 psi. An intermediate pressure between the normal flowing pressure and the shut-in pressure is then selected as the well preselected pressure. The predetermined pressure may then be chosen in the pressure range between the well normal flowing pressure and the well full bore flowing pressure. For this disclosure the preselected well pressure will be 2,750 psi and the full bore pressure of 2,200 psi becomes the predetermined well pressure for setting the delaying spring 67.

The upward urging force of the balance spring means 67 is then adjusted to enable the piston 71 to move the sleeve 61 downwardly sufficiently to align the windows 61k with the detent balls 60 when the pressure in the well decreases below the normal flowing pressure to the predetermined wide open flowing pressure.

The net movement effecting urging force on the piston 71 will be the difference between the charged pressure downwardly urging on the surface 71g and the pressure in the bore of the tubing upwardly urging on the surface 71d multiplied by the effective surface area. For example, if the effective surface area of the surface 71g and 71d is a half inch, the net downwardly urging force on the plunger 71 at the normal flowing well pressure of 2,500 psi with a charged pressure in the chamber 37 of 2,750 psi would be 250 psi times 0.5 square inches or pounds. The engagement of the detent balls 60 with the upper surface of the slots 61m in the lower portion of the sleeve 61- will limit downward movement of the sleeve 61 and the plunger 71 at the normal well flowing pressure. The distance the sleeve 61 must move downwardly from this position to engage the shoulder 66b of the balance member 66a in the upper position which enables the sleeve 61 to latch the balls 60 outwardly to lock the slide 33 in the lower portion is three-eighths of an inch. An additional threeeighths-inch downward travel of the sleeve 61 and engaged balance member 66 is needed to align the windows 61k with the detent balls 60 to release the slide 33 when the piston 71 urges downwardly thereon. The net downward pressure urging force on the piston 71 at the predetermined full bore flowing pressure of 2,200 psi will be 2,750 psi less 2,200 psi or 550 psi times 0.5 square inch equaling 275 pounds. The additional downward pressure or force on the plunger 71 between the normal and full bore flowing pressure is then determined, which, for this example, is 275 pounds less 125 pounds or pounds.

The spring constant of the spring 67 is known and the spring 67 is selected depending upon the determined urging force difference between the full bore pressure and the normal flowing pressure on the plunger 71. The spring 67 is first preloaded by compressing the spring to provide a 125-pound upwardly urging to the balance member 64 to equalize the 125-pound net downwardly urging or the plunger 71 imparted to the sleeve 61 resulting from the normal flowing pressure of 2,500 psi urging on the plunge 71. Preloading enables the sleeve 61 to move to engage the balance member 66 without moving the balance member 66 downwardly at normal well flowing pressure to effect a positive latch of the detent balls 60 by the sleeve 61. To establish the preload on the spring 67, the adjustment ring 67b is moved up wardly by rotating the adjustment ring 67b relative to the fixed spring keeper 67a to compress the spring 67b a calculated distance to provide the desired loadings. As the well pressure decreases from the normal flowing pressure to the predetermined full bore flowing pressure, the net downwardly force difference on the plunger 71 increases by 150 pounds. To effect a release of the detent balls 60 to rotate the ball 40 closed at the predetermined well pressure, the spring 67 is selected to compress a distance of three-eighths of an inch, to align the windows 61k with the detent balls 60 when the additional downwardly urging force of I50 pounds acts thereon. To provide such movement, a spring 67 having a spring constant of 400 pounds per inch is selected for installation in the tool. The prcload compression on the spring 67 of 125 pounds would require a livesixteenths of an inch compression of the spring 67. The tool is then assembled and taken to the job sight in the condition illustrated in FIGS. 1A, 1B, 1C, ID, 1E, and 1F.

At the well site, compressed gas, preferably nitrogen to prevent deterioration to the rubber diaphragm 34, is injected or charged into the system at port 35a to pressure the chamber 37 to the desired pressure. The flapper member 35d moves aside to enable flow through the port 34g into the chamber 37, but moves to cover the port 34g to block flow from the chamber 37 through the port 34g to maintain the preselected pressure in the chamber 37. Since the pressure responsive annular surfaces 71d and 71g have preferably the same effective surface area the pressure charged into the chamber 37 is the preselected well pressure. One skilled in the art may vary the size of the effective surface areas 71d and 71g to enable a different pressure to be charged into the chamber 37 to effect the desired downwardly reference urging on the piston 71.

When the pressure charge has been established in the chamber 37 and the supply of nitrogen is disconnected, the tool S is in the condition illustrated in FIGS. 2A, 2B, and 2C. The gas pressure in the chamber 37 moves the diaphragm 34 inwardly to fill the portion of the chamber 74 not filled with oil. The pressure of the gas in the chamber 37 is then transmitted through the oil in the chamber 74 to the piston surface 71d for urging the plunger 71 to move downwardly. Because the urging of the atmosphere pressure on shoulder 71d is much less than the charged pressure, the piston 71 moves downwardly from the upper or retracted position (FIGS. 18 and 1C) to the lower or extended position illustrated. The annular shoulder 71t of the piston 71 engages the shoulder 61f of the sleeve 61 to move the sleeve 61 downwardly to engage the uppwer shoulder 66b of the ring 66. Sincethe pressure differential of the piston 71 is greater than 150 pounds, the piston 71 will overcome the upwardly urging of the balance spring 67 to move the ring 66 downwardly. As the piston 71 moves downwardly, the detent balls 73 mounted thereon engage the annular shoulder 72f for moving the latch sleeve 72 downwardly with the plunger 71. The downward movement of the latch sleeve 72 continues until the plurality of balls 73 align with the plurality of windows 6111 in the latch sleeve 61. The upward urging of the spring 72d then wedges the balls 73 inwardly into the windows 61h of the locking sleeve 61. Such movement of the balls 73 unlocks or releases the latch sleeve 72 from the plunger 71 and enables the spring means 72d to move the latch sleeve 72 upwardly to the position illustrated in FIG. 2B with the balls 73 locked in the windows 61h of the sleeve 61.

The tool 20 is then secured beneath and sealed to the tubular mandrel by engagement with threads 31a. The

mandrel is then connected to a wire line running tool and the entire assembly is lowered down the bore of the production tubing to the subsurface position for securing the well tool S. The mandrel is then secured in the bore of the tubing and the wire line running tool rctrieved as is well known in the art. The mandrel is also provided with means for sealing between the outer surface of the mandrel and the inner surface of the bore of the tubing for directing the flow through the bore of the tubular mandrel as is also well known in the art.

With the well surface control valves closed, the well shut-in pressure is communicated through the port 71 to the pressure responsive surface 711110 urge the piston 71 to move upwardly. The well pressure communicated through the port 71d also urges on the upper shoulder 81c of the balance piston 81 to urge the balance piston downwardly to maintain the oil pressure in the expansible chamber 82 equal to the well shut-in pressure. This eliminates any pressure differential across the slide 33, the sleeve 63, the latch slide 72 or the plunger 71 which would damage, create stresses, or otherwise interfere with their operation.

Because the charged pressure in the chamber 37 urging downwardly on the piston 71 is less than the shut-in pressure urging upwardly on the shoulder 71d of the piston 71, the piston 71 moves upwardly to the position illustrated in FIGS. 5A, 5B, and 5C. The upward movement of the piston 71 also moves the sleeve 61 upwardly by engagement of the locked balls 73 with the upper edge of the window 61h until the balls 73 are aligned with the inner surface portion of the sleeve 72 above the annular shoulder 72f. The downward biasing of the spring 62 imparted to the sleeve 61 will then wedge the balls 73 outwardly above the shoulder 72f to release the locking sleeve 61 from the plunger 71. This enables the sleeve 61 to move downwardly until the upper edge of the slots 61m engage the balls 60 which limits further downward movement of sleeve 61 with the balls 73 remaining with the sleeve 72 above the shoulder 72a as illustrated in FIG. 3B.

To rotate the ball 40 to the aligned position enabling fluid flow through the bore of the tubing, a pump or other pressure generating means is connected to the bore of the tubing at the surface. The pressure in the bore of the tubing above the ball 40 is then increased until it is greater than the shut-in pressure of the well. The increased pressure produces a pressure differential across the ball 40 and the seat ring 41 to produce a downward urging force which overcomes the upward urging of the spring 50 to move the ball 40, the seat ring 41 and the slide 33 downwardly relative to the tubular member 31 (FIG. 3D). The downward acting force produced by the pressure urging on the ball 40 and the seat ring 41 is transmitted through the sleeve 44 to the slide 33 at engaged annular shoulders 44d and 33g (FIG. 1F).

As illustrated in FIGS. 3B and 3C, the downward movement of slide 33 moves the annular shoulder 33e below the plurality of balls 60 located in the window openings 63b of the sleeve 63. When the shoulder 336 of the slide 33 is below the balls 60 the biasing of the spring 62 urging the latch sleeve 61 downwardly wedges or forces the engaged balls 60 outwardly above the shoulder 33e with the tapered upper edge of the slots 61m. The latch 61 continues to move downwardly for three-eighths of an inch until the lower annular shoulder 61b engages the upper shoulder 66b of the balance member 66 to latch the balls 60. With the balls 60 locked above the shoulder 33c, the slide 33 is blocked from moving upwardly by the urging of spring 50 by engagement of the shoulder 33a of the slide 33 with the balls 60 positioned in the window 63h. As illustrated in FIG. 3A, the ball 40 is still closed and the piston 71 has the same well shut-in pressure and preselected charged reservoir pressure acting thereon and has not moved even though the pressure in the bore of the tubing above the ball 40 has been increased. The balance piston 81, to maintain a constant pressure in the chamber 82 equal to the shut-in pressure, moves downwardly to adjust for the change in volume of the chamber 82 by movement of the slide 33 downwardly to the lower position.

After locking the slide 33 in the lower position with the balls 60, the ball 40 is rotated to the open or aligned position, illustrated in FIG. 48 by venting or otherwise decreasing the pressure in the bore of the tubing above the ball 40. The reduced pressure urging downwardly on the ball 40 and the seat ring 41 enables the urging of the spring 44c to move the sleeve 44 upwardly. The

upward movement of the sleeve 44 also imparts an upward movement to the engage ball 40 and seat ring 41 relative to slide 33. 7

Relative longitudinalmovement of ball 40 to the slide 33 also moves the ball 40 relative to the pivot pins 43a secured to the slide 33. The upward movement of the ball 40 imparts a 90 rotation to the ball 40 for rotating the ball 40 to the aligned position for enabling flow of fluid through the bore of the tubing. Reference is made to my copending applications, Ser. No. 131,628, filed I Apr. 6, l97l, and related application, Ser. No.

214,734, filed Jan. 3, 1972, which illustrates in greater detail the relationship of the eccentric pins 43a and the ball 40 in rotating the ball 40 to the aligned position by the upward movement relative to the pins 43a from the closed position. The sleeve 44, the rotating ball 40 and the seat ring 41 moveupwardly until the upper annular shoulder 41b of the seat ring 41 engages the lower shoulder 31d of the fixed member 310.

With the ball 40 rotated to the aligned or open position, hydrocarbons and the like in the producing formation flow through the bore of the production tubing and the bore 25 of the well tool to the surface. Valves on the well surface control equipment are normally used to control the flow of the fluid through the bore of the tubing as is well known. When flow through the bore of the tubing is established, the well pressure in the bore of the tubing is reduced to the normal flowing well pressure which is less than the preselected well pressure established in the reservoir 37. With the well flowing pressure communicated through the port 71p to the shoulder surface 71d of the piston 71 less than the preselected pressure in the reservoir 37 urging on the shoulder surface 71q the plunger 71 is moved downwardly. The downward movement of the plunger 71 to the extended position also moves the latch slide 72 downwardly through engagement of the balls 73 with the shoulder 72:

The latch sleeve 72 continues to move downwardly with the plunger 71 until the detent balls 73 are aligned with windows 61h in the latch sleeve 61. When aligned with the windows 61h the lower tapered annular shoulder 72f wedges the balls '73 inwardly into the windows 61h by the urging of the spring means 72d to disengage the balls from the shoulder 72f and enable the spring 72d to move the released latch sleeve 72 upwardly. The upward movement of the latch sleeve 72 by the spring 72d locks the balls 73 in the windows 61h of the locking sleeve 61 to operably connect the plunger 71 and the locking sleeve 61.

When the well pressure in the bore of the tubing varies from the preselected well pressure the piston 71 will move to rotate the ball 40 closed. Should the well pressure increase as when the surface well control valve is closed, the greater shut-in pressure will urge on the shoulder 71d of the plunger 71 to overcome the downwardly urging of the preselected pressure in chamber 37 to move the plunger upwardly. The upward movement of the plunger 71 will engage the plurality of detent balls 73 with the upper surface of the windows 61h to overcome the downwardly urging imparted by the spring 61a to move the locking sleeve 61 upwardly. The upward movement of the sleeve 61 moves the slots 61m on the lower portion of the sleeve 61 to align with the balls 60, to unlock the detent balls and enable their movement from the annular shoulder 33e. With the detent balls 60 no longer locked, the upwardly movement imparted by the urging of the spring 50 wedges the balls 60 into the slots 61m and moves the slide 33 to the upper position.

The upper shoulder 41b of the seat ring 41 engaging the member 31c blocks upward movement of the ball 40 with the slide 33. This enables the eccentric pins 43a secured to the slide 33 to move upwardly relative to the ball 40 to rotate the ball 40 from the open position to the closed position. The movement of the ball 40 to the closed position from the open position is also illustrated in greater detail in. my copending applications referred to hereinabove.

With the ball 40 in the closed position, the flow of fluid in the bore of the tubing is blocked at both the subsurface location and at the well surface. Should the surface located control equipment be subsequently destroyed, damaged or otherwise impaired by fire or the like, the well tool Swill continue to block flow through the bore of the tubing to prevent a well blowout. When it is desired to produce the well again, it is only necessary to sequentially increase and then decrease the pressure in the bore of the tubing above the ball 40 to crank open the ball 40 to enable flow. A subsequent decrease to the normal well flowing pressure will again cock the piston 71 to enable imparting closing rotation to the ball 40 when the well pressure varies from the preselected pressure.

A decrease in well pressure below the preselected well pressure will enable the piston 71 to move the en gaged locking sleeve 61 downwardly to align the window 61k with the locked detent balls 60 to release the slide 33 and close the ball 40. Since the normal well flowing pressure is less than the pressure in the chamber 37 urging on the plunger 71, the plunger 71 will move downwardly to operably connect with the locking sleeve 61 by engagement of the detent balls 73. The lower annular shoulder 71t of the plunger 71 is also brought into engagement with the shoulder 61f of the locking sleeve 61 for imparting the downwardly urging of the piston 71 to the sleeve 61. The balance ring 66 will engage the sleeve 61 to block further downward movement of the engaged locking sleeve 61 because of the upward urging imparted to the balance member 66 by the spring means 67. By setting the preloaded upwardly urging force of the spring 67 with the keeper members 67a and 671), the upward urging of the normal well flowing pressure on the piston 71 and the upward urging of the spring 67 is equal to the downward urging of the pressure in the chamber 37 and the piston 71 and locking sleeve 61 will remain stationary as the well pressure varies from the preselected pressure to the normal flowing pressure. The ring member 64 secured with the tubular member 31 limits upward movement of the balance member 66 to maintain the locking sleeve 61 in the detent ball 60 locking position illustrated in FIGS. 38 and 3C.

As the well pressure continues to decrease below the normal well flowing pressure, the well pressure urging upwardly on the shoulder 71d for opposing the urging of the preselected pressure in the chamber 37 decreases. The increased downwardly urging on the piston 71 is imparted to the locking sleeve 61 by engagement of the annular shoulder 72! and the upward facing shoulder 61f of the locking sleeve 61. The downward urging of the plunger 71 will be opposed by the upwardly biasing spring 67 without movement of the plunger 71 until the preload set by adjusting members 67b and 670 on the spring 67 has been overcome. Additional piston movement delaying urging by the spring 67 result from compression of the spring 67 and downward movement of the balance member 66, the locking sleeve 61, and the plunger 71 (FIG. 2C). When the locking sleeve 61 has moved downwardly a sufficient distance to align the plurality of windows 61k with the detent balls 60, the balls 60 are free to move inwardly and out of locking engagement with the annular shoulder 3312 of the slide 33. The upward urging of the strong spring 50 then wedges or forces the balls 60 inwardly with the tapered annular surface 33e and moves the slide 33 upwardly to the position illustrated in FIG. 6B. The upwardly movement of the slide 33 rotates the ball 40 to the closed or transverse position as set forth hereinabove. By selecting a spring 67 having a spring constant to provide the desired movement and by adjusting the preload on spring 67, the predetermined pressure below the normal well flowing pressure at which the ball 40 is rotated closed may be precisely and accurately determined. This feature is a significant advantage in a well having ahigh allowable normal flow.

In subsequently opening the ball 40 by increasing the pressure in the bore of the tubing above the ball 40, the annular shoulder 33e is again moved below the balls 60 for enabling the balls 60 to move outwardly. The upward urging of the stronger spring 67 on the balancing member 66 will overcome the downward urging of the spring 62 on the locking sleeve 61 to urge the locking sleeve 61 to move upwardly to the locking position illustrated in FIG. 3B, for locking the slide 33 in the lower position.

If the well tool S malfunctions, the well tool S and connected mandrel 21 may be retrieved back to the surface with a wire-line retrieval tool. A properly operating well tool S may then be run in the bore of the tubing T, without the need to kill the well and pull the tubing T to replace the safety valve. While the preferred embodiment of the present invention is a wire-line run and retrieved safety valve, the invention may be employed without that feature by simply securing the tool S in the bore ofa well tubing joint which would then be included in the flow control housing F. The tubing joint thus forming a portion of the flow control assembly F would then be connected in the well tubing string at the desired location.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.

What is claimed is:

l. A well tool positioned in the bore of a Well tubing at a subsurface location in the well for controlling flow of well fluids through the bore in response to pressure changes of the well fluids in the bore of the tubing comprising:

a. a flow control assembly securable in the bore of the well tubing;

b. bore closure means mounted with said flow control assembly for movement to and from an open position enabling flow of fluid through the bore of the tubing and a closed position blocking flow of well fluids through the bore of the tubing; and

c. means for effecting movement of said bore closure means to the closed position when the pressure in the bore of the tubing is varied both above a preselected well pressure or below the pre-selected well pressure wherein flow of fluid through the bore of the tubing is controlled.

2. The structure as set forth in claim 1 including:

means for effecting movement of said bore closure means to the'open position for enabling flow of fluid through the bore of the tubing.

3. The structure as set forth in claim 1, wherein:

said bore closure means includes a ball-type valve rotatable between open and closed positions for controlling flow of fluid through the bore of the tubing.

4. The structure as set forth in claim 1, including:

means for equalizing the urging of the well pressure on said flow control assembly to provide a large flow passage through the bore of the tubing adjacent said flow control assembly for the well fluids.

5. The structure as set forth in claim 1, wherein:

said means for effecting movement of said bore closure means to the closed position includes a piston means operably connected with said bore closure means for moving in response to the urging of the pressure in the bore of the tubing to operate said bore closure means wherein said piston means movements operate to close said bore closure means.

6. The structure as set forth in claim 5, including:

means with said piston means for urging said piston means to move when the pressure in the bore is below a preselected pressure in a direction opposite the direction of movement provided by the urging of the pressure'in the bore to move said bore closure means to the closed position wherein the pressure in the bore of the tubing enables said piston means to move to control the flow through the bore of the tubing.

7. The structure as set forth in claim 6, wherein:

said means for urging said piston means to move in a direction opposite the direction of movement provided by the urging of the pressure in the bore includes a chamber formed by said flow control assembly adjacent said piston means and having a charged pressure established therein for urging on said piston means.

8. The structure as set forth in claim 6, including:

balancing means for providing an urging on said piston means to control movement thereof by said means for urging said piston for so long as the pressure in the bore of the tubing is a value less than the preselected pressure and greater than a predetermined pressure wherein the piston means moves to control the flow through the bore of the tubing when the pressure in the bore is less than the predetermined pressure.

9. The structure asset forth in claim 8, wherein:

said balancing means includes a spring means mounted with said flow control assembly and engageable by said piston means when the pressure in the bore is less than the preselected pressure, said spring means being overcome by said means for urging when the pressure in the boreof the tubing is less than the predetermined pressure wherein said piston means moves to operate said bore closure means to control flow of fluid through the bore of the tubing.

10. The structure as set forth in claim 1, wherein said flow control assembly includes:

a. a carrier member secured in the bore of the tubing;

and

b. a slide member movably connected with said carrier member and mounting said bore closure means, said slide member movably to and from a first position enabling said bore closure means to move to the open position and to and from'a second position for moving said bore closure means to the closed position wherein said slide member movement enables said bore closure means to control flow of fluid. through the bore of the tubing.

11. The structure as set forth in claim 10, wherein:

said means for effecting movement of said bore closure means to the closed position includes a piston means, operably connected with said slide means, for moving in response to the urging of the pressure in the bore of the tubing to enable movement of said slide means to the second position wherein said bore closure means is moved to control the flow of fluid through the bore of the tubing.

12. The structure as set forth in claim 11, wherein:

said flow control assembly further includes means for releasably locking said slide member in the first position, said means for locking releasable by movement of said piston means to thereby enable movement of said slide means to the second position wherein said bore closure means is moved to the closed position to control the flow of fluid through the bore of the tubing.

13. The structure as set forth in claim 12, wherein said means for releasably locking said slide member includes: I

a. said slide member having a surface with a recess therein;

b. a detent movably mounted with said flow control assembly to align with said recess when said slide in the first position, said detent adapted to move into said recess when aligned therewith; and

- c. latch means for moving to latch said detent in said recess when said slide member is in the first position wherein said bore closure is enabled to move to the open position to effect flow of fluid through the bore of the tubing.

14. The structure as set forth in claim 13, wherein:

said piston means is moved by the pressure in the bore of the tubing to move said latch means to re lease said detent from said recess enabling said slide member to move to the second position wherein said bore closure means is moved to the closed position for controlling flow of fluid through the bore of the tubing.

15. The structure as set forth in claim 12, including:

means for equalizing the urging of the well pressure on said means for-releasably locking said slide to provide a larger flow passage through the bore of the tubing adjacent said flow control housing.

16. The structure as set forth in claim 12, including:

means for effecting movement of said bore closure means to the open position for enabling flow of fluid through the bore of the tubing when said slide is in the first position.

17. The structure as set forth in claim 16, wherein:

said bore closure means includes a ball-type valve rotatable between open and closed positions for controlling flow of fluid through the bore of the tubing.

18. The structure as set forth in claim 11, including: balancing mean balancing means for providing an urging on said piston means to control movement thereof for so long as the pressure in the bore of the tubing is less than the preselected pressure and greater than a predetermined pressure wherein said piston means moves to operate said bore closure means to control the flow of fluid through the bore of the tubing when the pressure is less than the predetermined pressure.

19. The structure as set forth in claim 18, wherein:

said balancing means includes a spring means having one end mounted with said flow control assembly and the other end engageable with said piston means when the pressure in the bore is less than the preselected pressure, the urging of said spring means being overcome when the pressure in the bore is less than the predetermined pressure wherein said piston means moves to control flow of fluid through the bore of the tubing.

20. A well tool mountable with a well tubing for controlling flow of well fluids through the bore of the well tubing at a subsurface location in the well, including:

a. a member mountable with the tubing at a subsurface location;

b. bore closure means movably mounted with said member for movement to and from an open position enabling flow of well fluids through the bore of the tubing and a closed position blocking flow of well fluids through the bore of the tubing; and

0. means for effecting movement of said bore closure means to the closed position when the pressure of the well fluids in the bore of the tubing is varied both above or below a preselected well pressure the preselected well fluid pressure wherein flow of well fluids through'the bore of the tubing is controlled. V

21. The structure as set forth in claim 20, wherein:

said bore closure means includes a ball-type valve rotatable between open and closed positions for controlling flow of fluid through the bore of the tubing.

22. A valve apparatus adapted to be positioned in the bore of a well tubing for controlling flow of well fluids through the bore of the well tubing, comprising: 

1. A well tool positioned in the bore of a well tubing at a subsurface location in the well for controlling flow of well fluids through the bore in response to pressure changes of the well fluids in the bore of the tubing comprising: a. a flow control assembLy securable in the bore of the well tubing; b. bore closure means mounted with said flow control assembly for movement to and from an open position enabling flow of fluid through the bore of the tubing and a closed position blocking flow of well fluids through the bore of the tubing; and c. means for effecting movement of said bore closure means to the closed position when the pressure in the bore of the tubing is varied both above a preselected well pressure or below the pre-selected well pressure wherein flow of fluid through the bore of the tubing is controlled.
 2. The structure as set forth in claim 1 including: means for effecting movement of said bore closure means to the open position for enabling flow of fluid through the bore of the tubing.
 3. The structure as set forth in claim 1, wherein: said bore closure means includes a ball-type valve rotatable between open and closed positions for controlling flow of fluid through the bore of the tubing.
 4. The structure as set forth in claim 1, including: means for equalizing the urging of the well pressure on said flow control assembly to provide a large flow passage through the bore of the tubing adjacent said flow control assembly for the well fluids.
 5. The structure as set forth in claim 1, wherein: said means for effecting movement of said bore closure means to the closed position includes a piston means operably connected with said bore closure means for moving in response to the urging of the pressure in the bore of the tubing to operate said bore closure means wherein said piston means movements operate to close said bore closure means.
 6. The structure as set forth in claim 5, including: means with said piston means for urging said piston means to move when the pressure in the bore is below a preselected pressure in a direction opposite the direction of movement provided by the urging of the pressure in the bore to move said bore closure means to the closed position wherein the pressure in the bore of the tubing enables said piston means to move to control the flow through the bore of the tubing.
 7. The structure as set forth in claim 6, wherein: said means for urging said piston means to move in a direction opposite the direction of movement provided by the urging of the pressure in the bore includes a chamber formed by said flow control assembly adjacent said piston means and having a charged pressure established therein for urging on said piston means.
 8. The structure as set forth in claim 6, including: balancing means for providing an urging on said piston means to control movement thereof by said means for urging said piston for so long as the pressure in the bore of the tubing is a value less than the preselected pressure and greater than a predetermined pressure wherein the piston means moves to control the flow through the bore of the tubing when the pressure in the bore is less than the predetermined pressure.
 9. The structure as set forth in claim 8, wherein: said balancing means includes a spring means mounted with said flow control assembly and engageable by said piston means when the pressure in the bore is less than the preselected pressure, said spring means being overcome by said means for urging when the pressure in the bore of the tubing is less than the predetermined pressure wherein said piston means moves to operate said bore closure means to control flow of fluid through the bore of the tubing.
 10. The structure as set forth in claim 1, wherein said flow control assembly includes: a. a carrier member secured in the bore of the tubing; and b. a slide member movably connected with said carrier member and mounting said bore closure means, said slide member movably to and from a first position enabling said bore closure means to move to the open position and to and from a second position for moving said bore closure means to the closed position wherein said slide member movement enables said bore closure means to control flow of fluid through the bore of the tubing.
 11. The structure as set forth in claim 10, wherein: said means for effecting movement of said bore closure means to the closed position includes a piston means, operably connected with said slide means, for moving in response to the urging of the pressure in the bore of the tubing to enable movement of said slide means to the second position wherein said bore closure means is moved to control the flow of fluid through the bore of the tubing.
 12. The structure as set forth in claim 11, wherein: said flow control assembly further includes means for releasably locking said slide member in the first position, said means for locking releasable by movement of said piston means to thereby enable movement of said slide means to the second position wherein said bore closure means is moved to the closed position to control the flow of fluid through the bore of the tubing.
 13. The structure as set forth in claim 12, wherein said means for releasably locking said slide member includes: a. said slide member having a surface with a recess therein; b. a detent movably mounted with said flow control assembly to align with said recess when said slide in the first position, said detent adapted to move into said recess when aligned therewith; and c. latch means for moving to latch said detent in said recess when said slide member is in the first position wherein said bore closure is enabled to move to the open position to effect flow of fluid through the bore of the tubing.
 14. The structure as set forth in claim 13, wherein: said piston means is moved by the pressure in the bore of the tubing to move said latch means to release said detent from said recess enabling said slide member to move to the second position wherein said bore closure means is moved to the closed position for controlling flow of fluid through the bore of the tubing.
 15. The structure as set forth in claim 12, including: means for equalizing the urging of the well pressure on said means for releasably locking said slide to provide a larger flow passage through the bore of the tubing adjacent said flow control housing.
 16. The structure as set forth in claim 12, including: means for effecting movement of said bore closure means to the open position for enabling flow of fluid through the bore of the tubing when said slide is in the first position.
 17. The structure as set forth in claim 16, wherein: said bore closure means includes a ball-type valve rotatable between open and closed positions for controlling flow of fluid through the bore of the tubing.
 18. The structure as set forth in claim 11, including: balancing mean balancing means for providing an urging on said piston means to control movement thereof for so long as the pressure in the bore of the tubing is less than the preselected pressure and greater than a predetermined pressure wherein said piston means moves to operate said bore closure means to control the flow of fluid through the bore of the tubing when the pressure is less than the predetermined pressure.
 19. The structure as set forth in claim 18, wherein: said balancing means includes a spring means having one end mounted with said flow control assembly and the other end engageable with said piston means when the pressure in the bore is less than the preselected pressure, the urging of said spring means being overcome when the pressure in the bore is less than the predetermined pressure wherein said piston means moves to control flow of fluid through the bore of the tubing.
 20. A well tool mountable with a well tubing for controlling flow of well fluids through the bore of the well tubing at a subsurface location in the well, including: a. a member mountable with the tubing at a subsurface location; b. bore closure means movably mounted with said member for movement to and from an open position enabling flow of well fluids through the bore of the tubing And a closed position blocking flow of well fluids through the bore of the tubing; and c. means for effecting movement of said bore closure means to the closed position when the pressure of the well fluids in the bore of the tubing is varied both above or below a preselected well pressure the preselected well fluid pressure wherein flow of well fluids through the bore of the tubing is controlled.
 21. The structure as set forth in claim 20, wherein: said bore closure means includes a ball-type valve rotatable between open and closed positions for controlling flow of fluid through the bore of the tubing.
 22. A valve apparatus adapted to be positioned in the bore of a well tubing for controlling flow of well fluids through the bore of the well tubing, comprising: a. a flow control assembly securable in the bore of the well tubing; b. bore closure means mounted with said flow control assembly for movement to and from an open position enabling flow of fluid through the bore of the tubing and a closed position blocking flow of well fluids through the bore of the tubing; c. means for moving said bore closure means to and from the open and closed positions; and d. means enveloping said means for moving said bore closure means for equalizing the urging of the well pressure on said means for moving to provide a larger flow passage through the bore of the tubing adjacent said flow control assembly for the well fluids. 